For example, as disclosed in Japanese Unexamined Patent Publication JP-A2000-96625, a working machine for construction such as a backhoe has a crawler travelling device and an excavation working device, mounting an engine and installing a working device while mounting a cabin which surrounds an operating device and driver's seat on a rotatable device frame, placing hydraulic equipment on a pedestal of the device frame, disposing and attaching an attachment body of a front lower part of the cabin onto an installation part on a front part of the pedestal, providing a front cover between the front part of the pedestal and the front lower part of the cabin for covering forward and outward of the hydraulic equipment, and providing a front plate on the front lower part of the cabin for supporting a lower edge of a front glass.
And the cabin is intended to be mounted on the device frame after assembled separately from a side of the device frame. The cabin has a structure that, a stepped part and attachment body of a floor seat on a bottom of the cabin are positioned lowermost, a lower edge of the front plate of the cabin is substantially at the same level in height as that of the stepped part, and the stepped part is placed immediately above the front cover.